Thyroid indicators during pregnancy include T3, T4, and thyroxine. The level of thyroxine should be between 65-155 mmol/L and the serum thyroxine level should be between 10.3-25.7 nmol/L. If thyroid indicators are unstable during pregnancy, hypothyroidism or hyperthyroidism need to be treated promptly. Hypothyroidism in pregnant women can cause a restriction in fetal growth and development and therefore needs to be treated actively. If hyperthyroidism is present, it can cause miscarriage, premature birth, gestational hypertension and fetal malformation, skin dysplasia and esophageal atresia. Treatment with medication is required and needs to be maintained over a long period of time, and regular checkups should be conducted after delivery.